ESXi 5.5 with PowerPath/VE 5.9 - Inaccessible Local Datastores

After upgrading an ESXi Host to version 5.5 and installing the current multipathing driver from EMC (PowerPath/VE 5.9) I encountered a problem with the local storage. EMC PowerPath claims the local storage and makes it inaccessible. The ESXi is unable to boot after it tried to claim the local devices. It boots one last time after installing the driver but can't access the local VMFS datastore. After a second reboot, an error message "No hypervisor found." is displayed in the VMware Hypervisor Recovery mode. From now on, the ESXi Host does not boot and needs to be reinstalled.

The main cause for that issue can be found after the first (and last) reboot next to the PowerPath/VE 5.9 installation in /var/log/vmkernel.log:

How to get out of that situation?Do NOT reboot the ESXi Host in that situation! Disable the claimrule for PowerPath, reclaim the local device, remove PowerPath, set the bootstate to 0 and reboot the ESXi Host:

Identify the local Device with the vSphere Client. The local devices can be found in the Configuration Tab from the affected ESXi Host under Hardware -> Storage Adapters -> Paths

I spent a lot of time searching for a reason why I could not see my internal disks upon upgrading to ESXi 5.5. I thought it was something to do with PowerPath but could not find a way of removing/upgrading it on the host. It would fail with message: VIB cannot be removed live or something along those lines.